Open Drain External Stepper Drivers

[Brad]

Hi, I'm having issues with setting up a Genuine Smoothieboard with external stepper drivers (Stepperonline DM556T) I have set up the config file to use open drain for the enable, step, and direction. The manual for the stepper driver says "pulse active at rising edge; 4-5V when PUL-HIGH, 0-0.5V when PUL-LOW". I'm having issues with getting the pulse voltage low enough and I'm testing off the Direction pin. I'm pulling 5v from one of the endstop's power pins and have a DMM hooked up to a ground pin on a different endstop when testing the STP,ENA,DIR pins located on the driver.

Each + pin is at 5V

The ENA - pin is at 0.58v (even unplugging the enable pin circuit doesn't cause the motor to work)

The STP - pin is at 4.05v

the DIR - pin is at 4.05V when commanded to move one way and .058V when commanded to move the other way.

The stepper that is connected to this driver doesn't do anything when trying to move and I think its because the board isn't pulling the logic signal low enough for the driver to register that it is a pulse. Is there any way that I can get the open drain configuration to pull the voltage lower than 0.58V? I have used cheap TB6600 stepper drivers this way and they haven't had issues even though they say they require the same logic signal current as the Stepper online driver.

If there's anyone else who has used these stepper drivers and had success please let me know how you fixed this issue.

Thank you,

Brad

[Brad]

I ordered some logic line converters to give that a try because that was the other option for external drivers so I can give it a try using the non open drain option, hopefully that works. I am still open to other solutions but I couldn't think of any ways that I could get the board to drop the voltage lower than 0.58V. I'm hoping this works out but if there are other options I would love to hear them.

Thank you for your time.

[Arthur Wolf]

Try just wiring the ena pins together/shut ( ie don't try to control them ) and see if it works that way, as a test.

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勇気とユーモア

[golfopeos]

I can't really help, but i use some similar DM556 with smoothieboard v1 using open drain and this work like a charm excepted for the pin 4.29 (ena5)

Did you correctly configure the open drain pin in config file ?

my working config :

alpha_steps_per_mm                           800              # Steps per mm for alpha ( X ) stepper
alpha_step_pin                               2.0o             # Pin for alpha stepper step signal
alpha_dir_pin                                0.5o             # Pin for alpha stepper direction, add '!' to reverse direction
alpha_en_pin                                 0.4!o            # Pin for alpha enable pin
alpha_current                                2.7              # M1 stepper motor current
alpha_max_rate                               7000.0           # Maximum rate in mm/min

beta_steps_per_mm                            800              # Steps per mm for beta ( Y ) stepper
beta_step_pin                                2.1o             # Pin for beta stepper step signal
beta_dir_pin                                 0.11!o           # Pin for beta stepper direction, add '!' to reverse direction
beta_en_pin                                  0.10!o           # Pin for beta enable
beta_current                                 2.7              # M2 stepper motor current
beta_max_rate                                7000.0           # Maxmimum rate in mm/min

gamma_steps_per_mm                           800              # Steps per mm for gamma ( Z ) stepper
gamma_step_pin                               2.2o             # Pin for gamma stepper step signal
gamma_dir_pin                                0.20!o           # Pin for gamma stepper direction, add '!' to reverse direction
gamma_en_pin                                 0.19!o           # Pin for gamma enable
gamma_current                                2.7              # M3 stepper motor current
gamma_max_rate                               500.0            # Maximum rate in mm/min

Br

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[Moi Toi]

Maybee you can also try to use series resistor for decrease voltage like is done for use with more than 5v logic ???

[Bdownhill]

Golfopeos here is a portion of the config that configures the open drain. I think it is correct for open drain, I have also tried them with a ! on each pin to see if that would work and found that would have the same results.

alpha_step_pin                               2.0o              # Pin for alpha stepper step signal
alpha_dir_pin                                0.5o              # Pin for alpha stepper direction, add '!' to reverse direction

alpha_en_pin                                 0.4o              # Pin for alpha enable pin
alpha_current                                1.5              # X stepper motor current
alpha_max_rate                               12000.0          # Maximum rate in mm/min

beta_step_pin                                2.1o              # Pin for beta stepper step signal

beta_dir_pin                                 0.11o             # Pin for beta stepper direction, add '!' to reverse direction
beta_en_pin                                  0.10o             # Pin for beta enable
beta_current                                 1.5              # Y stepper motor current
beta_max_rate                                12000.0          # Maximum rate in mm/min

gamma_step_pin                               2.2o              # Pin for gamma stepper step signal

gamma_dir_pin                                0.20o             # Pin for gamma stepper direction, add '!' to reverse direction
gamma_en_pin                                 0.19o             # Pin for gamma enable
gamma_current                                1.5              # Z stepper motor current
gamma_max_rate                               1000.0            # Maximum rate in mm/min

Arthur I did test the enable pin with it connected it's providing 5v to the driver and the stepper is easily turned by hand. When I unplug the enable connector on the driver the stepper becomes active and cant be turned by hand. I have tried the en pin with and without a ! and both ways the stepper can easily be turned if the enable connector is connected on the driver. The manual for the driver says that unplugged is active by default. That would mean that the board isn't pulling the signal low enough to enable the driver, is that correct?

Unrelated question for Arthur can a Solid State Relay use a PWM capable pin or does it have to be a PWM and Interrupt capable pin? I have an X5 board and need to control 3 SSRs but would like to keep the mosets free so I'm curious if I can use P3.25, and P3.26 next to the SD card slot or any of the P0.15-P0.18 pins in the middle of the board?

On Tue, May 19, 2020 at 3:40 AM Moi Toi <golf...@gmail.com> wrote:

Maybee you can also try to use series resistor for decrease voltage like is done for use with more than 5v logic ???

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[wolfmanjm]

http://smoothieware.org/lpc1769-pin-usage

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[Brad]

Wolfmanjm do you know if a SSR can be used on a PWM pin or does it need to be a PWM with Interrupt pin? I think I don't fully understand the difference between a PWM and Interrupt pin. Is an interrupt pin limited in how quickly it can switch? While a PWM pin can switch quickly but can't sustain a high or low signal for a long period of time? 2 of my SSRs will be for extruder heaters and 1 will be for a chamber heater all 3 at 120V AC so they won't be under the switch module.

[Golfo]

Yes you are right for interrupt capabilities but this is only used for input.

PWM pin is for manage some variable output (but can be a pwm reading input) I think with last firmware you can use any pin with a software PWM output (more slow than a PWM capable pin)

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